He was nicknamed the "gangsters' lawyer", one of the giants of the French legal system.

Olivier Metzner was a larger-than-life figure known for his spirited defence of high-profile and controversial defendants.

They included Panama's former dictator Manuel Noriega, rogue trader Jerome Kerviel and Continental Airlines, accused of causing the Concorde crash in 2000.

But his sudden death at 63 has shocked the legal world after his body was found near his private island in Brittany, with a suicide note discovered at his home nearby. "I had strong intellectual admiration for him, but that didn't stop me from thinking - wrongly it seems - that he could perhaps lack some heart and sensitivity," his colleague Georges Kiejman said.

I had strong intellectual admiration for him, but that didn't stop me from thinking - wrongly it seems - that he could perhaps lack some heart and sensitivity

Another associate, Antonin Levy, said Metzner's death was a huge loss to the French bar. He described him as a "great lawyer and a fighter".

In recent years, Metzner had argued for former prime minister Dominique de Villepin in the Clearstream scandal and represented rock star Bertrand Cantat when he was accused of killing his actress girlfriend.

He also argued the case of Francoise Bettencourt-Meyers, who tried to have her ailing mother, the L'Oreal heiress Liliane Bettencourt, declared a ward of court.

In 2010, he defended Noriega, who was eventually found guilty of money laundering and sent to jail for seven years in France.

Noriega, later extradited to Panama for further crimes, said in a note sent by his eldest daughter he was "surprised" and "deeply hurt" to learn of the death.

He also staunchly rejected suggestions of suicide, saying the act was "incompatible with (Metzner's) personality".

Metzner was also acting for French shipbuilding giant DCNS in a French court inquiry initiated by a Malaysian human rights group last year.

The tribunal was set up to investigate claims of corruption over a multi-billion ringgit sale of two Scorpene submarines by DCNS to Malaysia

Named France's most powerful lawyer by GQ magazine last year, Metzner was often to be seen standing at the top of the Palais de Justice's monumental steps, puffing on a cigar.

In court, he would pick holes in legal procedure to get clients off the hook. He was so successful that Liberation magazine described him as the "criminal fraternity's specialist".

Outside the courts, Metzner was a discreet figure.

Born in 1949 to farmers in Normandy, whose ancestors had fled Prussia in the 19th century, Metzner described himself as the product of a modest but "rigorous Normand and Protestant education".

He chose law after devouring the works of Kafka and reading about a shepherd who had been sentenced to death.

"He was from the mountains and incapable of explaining his defence in any understandable language. It made me want to be an interpreter for those who had difficult expressing themselves in front of the court and at the same time explain the justice system to them," he once said. Decades after his first case, in which he successfully defended a thief, his hourly fee had risen to €450 (HK$4,566).

Metzner never married and described himself as "left-wing at heart". In 2010 he bought Boedic Island in Brittany's Morbihan Gulf, a natural harbour on France's western coast.

Sources said his body was found floating near the island around 10am on Sunday.

A suicide letter was left at his house on the island, they said. The gendarmerie confirmed the death but refused to give details.

Additional reporting byAgence France-Presse

This article appeared in the South China Morning Post print edition as Suicide riddle of 'lawyer to rogues'